In the past, it has been proposed that heat dissipating properties for circuit boards be increased by affixing a thick metal plate or heat sink to the back of the printed circuit board. While this method has enjoyed much use in the past, it does have serious drawbacks. Since the metal plate is capable of absorbing heat from the components during normal operation of the circuit board, the metal plate is also capable of absorbing heat during any soldering process and thereby requiring an increased amount of time that the circuit board and plate combination is in a soldering machine which is known to be undesirable.
Also in the past, it has been proposed to provide for E/M shielding of various sections of a circuit board by placing a conductive cover on top of the circuit board over the area to be shielded. While this method of E/M shielding has received extensive use in the past, it too has serious drawbacks. Frequently the degree of E/M shielding is not sufficient for some purposes and consequently the performance of the circuit is degraded.
Also in the past it has been proposed to use a fixture device having several protuberances thereon for applying pressure to selective areas on a printed circuit board during the vapor phase soldering process. While this method has been used in the past, it too does have some drawbacks. The several protuberances often fail to provide an even distribution of pressure across the circuit board allowing for areas where the soldering process fails to be optimal.
Consequently, there exists a need for improving RF circuit boards and their method of manufacture.